Remote control system for a vehicle

ABSTRACT

A remote control system for precisely identifying a distance from the vehicle to an entry key and favorably controlling a vehicle-mounted device such as a door corresponding to the distance. The system comprises a transmitter transmitting different types of response demand signals within a predetermined communication area outside the vehicle, a vehicle mounted receiver for receiving a response signal released from a portable transmitter/receiver in response to the reception of the response demand signal, a controller controlling the vehicle mounted device corresponding to the reception of the response signal by the vehicle mounted receiver. Locking and/or unlocking door(s) of the vehicle are controlled on the basis of whether or not the receiver receives the response signal to a response demand signal other than one having the largest communication area.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a remote control system for avehicle which can automatically lock and unlock the door(s) of a vehiclein wireless communication and more particularly to a remote controlsystem for a vehicle which can automatically lock the door(s) of avehicle when a user (driver) who carries with him an electronic or entrykey (with a portable transmitter/receiver) which includes anidentification code assigned to the vehicle walks away a predetermineddistance from the vehicle and automatically unlock the same when theuser comes back to the distance.

[0003] 2. Description of the Related Art

[0004] Lock/unlock remote-control systems for vehicle doors are knownhaving a so-called, “welcome function”. In the systems, every user(driver) of a vehicle owns an entry key (with a portabletransmitter/receiver) which upon receiving a response demand signal thatis transmitted from a transmitter installed in the vehicle and isreceivable within a predetermined range about the vehicle (which may bereferred to as “having a predetermined communication area” hereinafter),can transmit a response signal carrying a unique identification codeassigned in advance to each vehicle. When the user walks away from thepredetermined range of the vehicle and its entry key is disabled toreceive the response demand signal and thus to transmit back theresponse signal, the door of the vehicle is automatically locked. Whenthe entry key moves into the predetermined range and its response demandsignal is received by the transmitter/receiver which then responsesthereto to send back a response signal, the door is automaticallyunlocked.

[0005] For example, some of such conventional “welcome function” basedlock/unlock remote-control systems for vehicle doors are disclosed inJapanese Patent Laid-open Publications (Heisei)5-106376 and(Heisei)10-25939 in which a transmitter mounted on a vehicle is providedfor intermittently transmitting a response demand signal having apredetermined communication area and, when receiving a signal respondingto the response demand signal from an entry key which is carried by theuser of a vehicle and moves into the predetermined communication area,examining whether the response signal is valid (regular) or not (welcomecode examination). When the response signal has been examined to bevalid, the door(s) of the vehicle is automatically unlocked. On thecontrary, when the response signal is not valid or when the entry keystays out of the predetermined communication area and thevehicle-mounted transmitter receives no response signal, the doorremains locked.

[0006] Accordingly, when the user of the vehicle carrying the entry keysimply walks away from the predetermined range of the vehicle, the doorof the vehicle can automatically be locked without paying any attentionto or operating the entry key. When the user comes into the range, thedoor can automatically be unlocked. This requires no boresome actions ofunlocking the door for riding the vehicle as well as contributes to theprevention of failing to lock door(s), and of vehicle theft.

[0007] The conventional systems have some advantages, particularly oncethe communication area is preset to a smaller size (for example, onemeter in radius), the systematic locking of the door can easily beconfirmed after getting off the vehicle, the power consumption fortransmitting signals can be as small as not hostile to a battery, andthe ID code (uniquely assigned to a vehicle) can hardly be interceptedby any other parties. The locking of the door may be easily confirmed byauditorily and visually perceiving the sound of a door locking mechanismand the shift of an inside door lock knob to the lock position.

[0008] Another conventional system disclosed in Japanese PatentLaid-open Publication (Heisei)10-153025 is provided in which atransmission antenna for detecting the approaching of an object into amiddle-sized area around a vehicle is mounted on the vehicle in additionto an antenna for transmitting the response demand signal. Upondetecting the approaching of the object or a driver into themiddle-sized area, the vehicle releases the response demand signal witha small-sized predetermined communication area and, when receiving aresponse signal to the response demand signal from the entry key of theright driver, unlock the door. Also, a second transmitting means havinga greater communication area is provided for locking the door. The dooris thus locked when the communication to the entry key with the secondtransmitting means is disabled.

[0009] According to the conventional systems, when the communicationarea for the response demand signal is set to be wide enough to detectthe driver approaching into the area of the vehicle at an earlieroccasion, the door(s) can be unlocked positively before the driverreaches the vehicle. This eliminates the need of the door being unlockedby the driver or user and provides the ease of getting in the vehiclewith operating only a door outer handle, hence improving the utility.

[0010] However, as the communication area is wide, the locking of thedoor will be carried out only when the user departs further from thevehicle, hence causing the user to confirm the door locking (throughlistening to the sound of the door locking mechanism or viewing theshift of the inside door lock knob to the lock position) with muchdifficulty. Also, while the user with the entry key walks about orpursues a job (e.g. ordering throughout the trunk room), the doorlocking is not performed and it may fail to protect articles in thevehicle from a thief.

[0011] In particular, when the user with the entry key is departing fromthe vehicle, its back is often turned to the vehicle. The wider thepredetermined communication area, the longer the period of the doorremaining unlocked is extended and thus the higher the risk of beingthieved will be increased. Also, the wider communication area requires ahigher level of power for transmitting the response demand signal andthe power consumption will be soared up drawing more power from thebattery.

[0012] For compensation, a modification is proposed such as disclosed inJapanese Patent Laid-open Publication (Heisei) 10-25939, where thecommunication area is reduced (about one meter in radius) allowing theresponse demand signal to be not received in a shorter distance from thedoor thus to lock the door. This permits the door locking to be easilyconfirmed, the ID code (ID number) to be hardly intercepted, and thepower for signal transmission to be minimized, hence lowering the powerconsumption.

[0013] However, the above modification will hardly ensure the unlockingof the door. It is common in the art for minimizing the powerconsumption for transmitting the response demand signal that theresponse demand signal from the vehicle is usually transmittedintermittently. With the wider communication area, the user moving inthe wider area is able to communicate with the vehicle, even if theresponse demand signal is transmitted with longer intermission period.Accordingly, the door is surely unlocked before the user arrives at thevehicle.

[0014] With the smaller communication area, however, when the userrushes to the vehicle in less time through the communication area, thecommunication between the vehicle-mounted transmitter and the entry keymay not be completed until the user arrives at the vehicle. This causesthe door to remain locked and its door outer handle may have to beoperated a number of times without success. As a result, the entry keysystem will be lost in commercial value. As a further modification, theperiod of the intermittent transmission of the response demand signalmay be shortened. This will however increase the power consumption andcause more power be drawn from the battery.

[0015] On the other hand, the conventional system disclosed in theabove-mentioned Japanese Patent Laid-open Publication (Heisei)10-153025allows the power for transmitting the response demand signal to bepossibly decreased, but it requires the extra transmission antenna fordetecting the invading of an object, hence increasing the complexity ofthe overall arrangement and thus the cost of the system. Also, the powerconsumption will be increased by the additional equipment. Moreover, theabove system transmits the response demand signal even when any otherpersonal or creature than the right entry key (user) advances close tothe vehicle, hence requiring more improvement for the power consumption.Since the communication area is too small to examine whether the entrykey is right or not as required before accepting the unlocking, the doormay remain not unlocked when the user or driver rushes to and arrives atthe vehicle. This will result in the misconduct of the automaticunlocking function.

SUMMARY OF THE INVENTION

[0016] An object of the present invention is to provide a remote controlsystem for a vehicle which can predictably control a vehicle mounteddevice such as a door of the vehicle corresponding to the distance fromthe vehicle to an entry key.

[0017] As a first feature of the present invention, the remote controlsystem for a vehicle comprises: a transmitter mounted on the vehicle fortransmitting a plurality of response demand signals which are receivablewithin different sizes of a predetermined range outside the vehicle; aportable transmitter/receiver for receiving the response demand signalsand sending back a response signal; a receiver mounted on the vehiclefor receiving the response signal sent back from the portabletransmitter/receiver; and a controlling means for controllingvehicle-mounted components corresponding to the reception of theresponse signal by the receiver, wherein said controlling means arrangedto control at least either unlocking or locking of the door(s) of thevehicle depending on whether the response signal to a type of theresponse demand signal other than a particular response demand signalbeing receivable in the largest size of the predetermined range isreceived or not by the receiver.

[0018] As a second feature of the present invention, the transmitterintermittently transmits different types of the response demand signalsreceivable within corresponding sizes of the predetermined range, andthe controlling means identifies a particular predetermined range wherethe portable transmitter/receiver is located on the basis of theinterval between receptions of the response signals and controls thevehicle-mounted components in a predetermined mode, corresponding to thesize of the predetermined range where the transmitter/receiver islocated.

[0019] As a third feature of the present invention, various types ofresponse demand signals are intermittently transmitted at differentintervals such that the transmission of one type of the response demandsignal receivable within a smaller predetermined range is transmitted atleast once between two adjacent transmitting timings of another type ofthe response demand signal receivable in a wider predetermined range.

[0020] As a fourth feature of the present invention, the responsesignals sent back from the portable transmitter/receiver arediscriminatable one another according to which size of the predeterminedrange of the respond demand signal that the respond signals respond to.

[0021] As a fifth feature of the present invention, when thedisembarkation of the user is detected and the user is departing fromthe vehicle, a type of the response demand signal receivable within thesmallest size of the predetermined range is transmitted from thetransmitter, and when the response signal showing reception of theresponse demand signal receivable in the smallest size of thepredetermined range is no more received by the receiver mounted on thevehicle, another type of the response demand signal receivable withinthe second smallest size of the predetermined range is begun to betransmitted from the transmitter and, in a similar manner, when theresponse signal to a type of the response demand signal receivable in arelatively smaller size of the predetermined range is no more receivedby the receiver mounted on the vehicle, a further type of the responsedemand signal receivable within a relatively larger size of thepredetermined range is begun to be transmitted in sequence from thetransmitter.

[0022] As a sixth feature of the present invention, when the entry keyis approaching to the vehicle and the response signal to the type of theresponse demand signal receivable within the largest size of thepredetermined range is first received by the receiver mounted on thevehicle, the response demand signal receivable within second largestsize of the predetermined range is transmitted from the transmitter andthen a response demand signal receivable within a relatively smallersize of the predetermined range is transmitted in sequence from thetransmitter.

[0023] As a seventh feature of the present invention, when theembarkation of the user is detected by the embarkation detecting means,a type of the response demand signal receivable within the vehicle istransmitted from the transmitter.

[0024] According to the first feature of the present invention, thedistance from the vehicle to the user carrying the portabletransmitter/receiver (entry key) can precisely be identified thus tocontrol the vehicle mounted device such as the door(s) at an optimumlength of the distance, hence improving the utility of controlling thevehicle mounted device such as unlocking and locking the door iscompatible with the anti-thief function.

[0025] According to the second feature of the present invention, thedistance range from the vehicle to the user carrying the portabletransmitter/receiver can be identified on the basis of the intervalbetween receiving timings of the sent-back response signal on thevehicle even if characteristic codes included in the response signalsare not different each other, which response signals are sent back fromthe portable transmitter/receiver that responds to a plurality types ofthe response demand signal receivable within their respective sizes ofthe predetermined ranges which are different each other. Hence, thevehicle mounted device can favorably be controlled depending on thedistance as well as the construction of the transmitter of the portabletransmitter/receiver and the code identifying action of the controllingmeans on the vehicle can significantly be simplified.

[0026] According to the third feature of the present invention, theresponse signal is also intermittently released from the portabletransmitter/receiver, thus providing the same effects and advantages asdescribed just above.

[0027] According to the fourth feature of the present invention, as theresponse signals released from the portable transmitter/receiver inresponse to reception of the response demand signal are different eachother based on the different sizes of the receivable ranges of thedemand signals, the distance from the vehicle to the portabletransmitter/receiver can be identified only from the response signalreceived and the optimum control of the device mounted on the vehiclecan be performed in accordance with the distance.

[0028] According to the fifth and sixth features of the presentinvention, at the disembarkation of the user, as the portabletransmitter/receiver carried by the user departs far from the vehicle,the transmission of the response demand signal receivable in a widersize of the predetermined range is executed in sequence and thetransmission of the response demand signal receivable in a smaller sizeof the predetermine range is canceled. As the potabletransmitter/receiver comes from far towards the vehicle, on the otherhand, the transmission of the response demand signal with a relativelysmaller predetermined receivable range is not executed before theresponse signal responding to the response demand signal with arelatively larger predetermined receivable range is received by thevehicle.

[0029] More particularly, while the portable transmitter/receiver is outof the largest predetermined receivable range, the response demandsignal receivable in the largest predetermined range only istransmitted. Only when the response signal responding to the responsedemand signal receivable in the largest predetermined range is receivedby the vehicle, the transmission of the response demand signal beingreceivable in a smaller size of the predetermine range and used foractually controlling the unlocking and locking of the door is executed.Therefore, the transmission of the response demand signal is minimizedhence reducing the consumption of a power from a battery equipped on thevehicle.

[0030] According to the seventh feature of the present invention, theuser carrying the portable transmitter/receiver in the vehicle canreadily be acknowledged, and the vehicle mounted device in the vehicleis controlled on the basis of the response signal from the portabletransmitter/receiver responding to a particular type of the responsedemand signal receivable within the vehicle, hence improving theanti-thief function.

BRIEF DESCRIPTION OF THE DRAWINGS

[0031]FIG. 1 is a block diagram showing a structure of the firstembodiment of the present invention;

[0032]FIG. 2 is a timing chart illustrating the automatic unlockingaction of a door in the first embodiment of the present invention whenthe driver carrying the entry key moves to the vehicle and embarks;

[0033]FIG. 3 is a timing chart illustrating the automatic locking actionof the door in the first embodiment of the present invention when thedriver disembarks and the entry key departs from the vehicle;

[0034]FIG. 4 is a part of the main flowchart showing an action of thefirst embodiment of the present invention;

[0035]FIG. 5 is the remaining part of the main flowchart showing anaction of the first embodiment of the present invention;

[0036]FIG. 6 is a flowchart showing the transmission of a responsedemand signal with timer interruption in the first embodiment of thepresent invention;

[0037]FIG. 7 is a flowchart showing a refresh 1 process in FIG. 4;

[0038]FIG. 8 is a flowchart showing a refresh 2 process in FIG. 4;

[0039]FIG. 9 is a flowchart showing a part of a welcome process in FIG.4;

[0040]FIG. 10 is a flowchart showing the remaining part of the welcomeprocess in FIG. 4;

[0041]FIG. 11 is a flowchart showing an immobilizing checking process inFIG. 4;

[0042]FIG. 12 is a flowchart showing the transmission of an I responsedemand signal with timer interruption in the first embodiment of thepresent invention;

[0043]FIG. 13 is a schematic view showing the relation between thecontrol operations and the distance from the vehicle to the entry key inthe first embodiment of the present invention;

[0044]FIG. 14 is a schematic view showing the relation between thecontrol operations and the distance from the vehicle to the entry key inanother embodiment of the present invention;

[0045]FIG. 15 is a diagram showing an exemplary format of the responsedemand signals preferably applicable to the present invention;

[0046]FIG. 16 is a diagram showing an exemplary format of the responsesignal for immobilizing operation preferably applicable to the presentinvention;

[0047]FIGS. 17 and 18 are main flowcharts showing the action of afurther embodiment of the present invention as combined;

[0048]FIG. 19 is a flowchart showing a part of a welcome process in FIG.17;

[0049]FIG. 20 is a flowchart showing the transmission of the responsedemand signal with timer interruption in a further embodiment of thepresent invention;

[0050]FIGS. 21A and 21B are a timing chart showing the transmission ofthe response demand signal in a still further embodiment of the presentinvention as combined;

[0051]FIG. 22 is a timing chart illustrating the automatic lockingaction of the door in the still further embodiment of the presentinvention when the driver disembarks and the entry key departs from thevehicle;

[0052]FIG. 23 is a timing-chart illustrating the automatic unlockingaction of a door in the still further embodiment of the presentinvention when the deriver carrying the entry key moves to the vehicleand embarks;

[0053]FIGS. 24 and 25 are main flowcharts showing in a combination theaction of the still further embodiment shown in FIGS. 22 and 23; and

[0054]FIG. 26 is a flowchart showing a part of a welcome process in FIG.24.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0055] An entry key system for a vehicle according to first embodimentof the present invention will be describe in more detail referring tothe accompanying drawings. Before starting the main description, somedefinitions on the flags at 1 of the bit and the timers employed in thedescription and the drawings are explained as listed below.

[0056] AREC=reception of A code;

[0057] ATM=transmission of A response demand signal;

[0058] BCHG=start of examining the shift from small B response demandsignal to large B response demand signal;

[0059] BLTM=transmission of large B response demand signal;

[0060] BREC=reception of B code;

[0061] BSTM=transmission of small B response demand signal;

[0062] I(variable)=the number of consecutive receptions of A code;

[0063] IMCHK=start of immobilizing checkup;

[0064] IMDONE=finish of immobilizing checkup;

[0065] IMOK=result of immobilizing checkup;

[0066] m(variable)=setting in timer T-OUT;

[0067] MOD(n,m)=remainder of n/m;

[0068] n(variable)=setting for the kind of response demand signals to betransmitted;

[0069] OUT=the entry key is out of communication area for A responsedemand signal;

[0070] RCHK=timer T-OUT has started for examining the entry key is notnear about vehicle;

[0071] RF1/2=finish of refresh procedure 1, 2, respectively;

[0072] T-BCHG=timer for setting exchange of B response demand signals;

[0073] T-IMCHK=timer setting time for immobilizing checkup;

[0074] T-OUT=timer setting time for judging that the entry key is out ofcommunication area for A response demand signal;

[0075] T-WR1/2=first and second timers each for measuring intervals ofsignal reception;

[0076] timer interrupt permission bit for response demand signal=timerinterruption permission for transmission of response demand signal.

[0077] A first embodiment of the present invention will be described inthe form of a remote control system for a vehicle referring to the blockdiagram of FIG. 1.

[0078] A smart entry unit 1 comprises a power supply circuit 2 such as abattery equipped on the vehicle, an input/output circuit 3 connected toLF (low frequency) transmitter circuits 9 a to 9 c, a bus communicationcircuit 4 connected by a communication line 32 to an ignition SW unit 10which will be described later, a memory circuit 5, an MOSFET circuit 6,an input circuit 7, and a CPU 8 connected to above-mentioned circuitcomponents for controlling their actions. The CPU 8 is further connectedto an RF receiver circuit 9 f. The input circuit 7 is connected to amanual SW 7 a for setting the system to a manual mode in which it isresponsive to only a manual code derived by manual operation from anentry key 50 which is described later, as well as a parking SW 7 b, fourdoor SWs 7 c, an engine hood SW 7 d, a door key cylinder SW 7 e, and soon.

[0079] The entry key 50 which is usually carried and manipulated by adriver or user of the vehicle comprises an RF circuit 51 fortransmitting an RF signal from an antenna, an alarm/display 52 such as abuzzer, a rectifier trigger (TRIG) circuit 53 for processing LF signalsreceived which are transmitted from the LF transmitter circuits 9 a to 9c, a CPU 54, a battery 55, manual switches 56 and 57 for transmittingmanual codes for manually locking and unlocking the door, and a switch58 for allowing/prohibiting the manual operation. The switches 56 and 57may be modified in to a single switch for repeating alternately the lockand unlock actions.

[0080] The ignition SW unit 10 comprises a bus communication circuit 11for exchanging signals via the communication line 32 with the smartentry unit 1, a power supply circuit 12, a memory circuit 13, animmobilizing (anti-thief functioning) antenna 14, a low frequency (LF)transmitter/receiver circuit 15, a key SW 16 for detecting theinsertion/extraction of a key, an ignition (IGN) SW 17, an IGN positiondetector 18 for detecting the contact position of the IGN SW 17, a motor19 for actuating a rotary contact of the IGN SW 17, a motor driver 20for driving the motor 19, an auxiliary (or emergency) key 21 which isinserted and extracted to and from the key cylinder, an interlock ACT(actuator) 22 for prohibiting the removal (or extraction) of theauxiliary key 21, an ACT driver 23 for driving the interlock ACT 22, anda CPU 24 for controlling the actions of the above-mentioned components.The CPU 24 is also connected to a quick start SW 31 for starting theengine.

[0081] The operation of the smart entry unit 1 and the entry key 50 willschematically be described referring to the timing charts of FIGS. 2 and3 and the schematic view of FIG. 13. FIGS. 2 and 3 illustrate thewelcome function in which the door of the vehicle is unlocked and lockedin response to the detection of the user carrying the entry key 50 (whomay hence be simply referred to “entry key” hereinafter) coming close tothe vehicle 1 for boarding and leaving from the vehicle 1 after gettingoff, respectively. In these figures, the height of the bars of theresponse demand signals represents the intensity of the signals thusindicating the size of the communication area (receivable range).

[0082] When the entry key is outside of and distanced significantly fromthe vehicle of which the door remains locked in a disembark or parkingmode, an A response demand signal (of e.g. 100 kHz) shown at the leftside end in FIG. 2 is transmitted from the vehicle at equal intervals ofa first predetermined time (y seconds) and with an intensitycorresponding to the maximum communication area (for example, 4 to 5meters in radius) denoted by A in FIG. 13. As the driver carrying theentry key moves into the communication area A for the A response demandsignal, the entry key receives the A response demand signal at themoment t1 and transmits a send-back signal or a response signalresponding to the A response demand signal which includes an A code andmay be referred to as “A code” hereinafter. The format of the responsesignal will be explained later in more detail referring to FIG. 15.

[0083] The vehicle, when receiving the response signal and judging thatthe response signal received is valid, releases a large-area B responsedemand signal (e.g. of 300 kHz and having a one-meter-radiuscommunication area denoted by B (large) in FIG. 13) from t2 at equalintervals of a second predetermined time (x seconds). It is assumed y>xor more specifically, y=3x in this embodiment. Upon receiving the Blarge response demand signal at t3, the entry key 50 releases a responsesignal which includes a B code and may be referred to as a “B code”hereinafter. When it is judged that the response signal including the Bcode is valid, the door of the vehicle is unlocked.

[0084] As the door is opened at t4 (door SW is on) and then closed att5, it is determined that the driver has embarked and an I(immobilizing) response demand signal designated its communication areaas in the interior of the vehicle is transmitted. When the entry keythen releases a response signal to the I response demand signal whichinclude an I code (immobilizing code), the vehicle carries outimmobilizing checkup (immobilizing code examination) for decidingwhether the I code received is valid or not. When the I code is valid,the transmission of the I response demand signal is canceled and anFI-ECU 33 is switched at t6 into the engine enabling mode.

[0085] Then, upon the ignition SW (IGN SW) being turned to the ONposition at t7, the transmission of both the A and B response demandsignals is stopped and simultaneously a refresh 2 process is commencedas will be described later. The transmission of the A and B responsedemand signals may be stopped, instead, upon judging that the I code isvalid or in response to the on/off action of the door switch triggeredby the opening and closing of the door.

[0086] The movement of the vehicle 1 is stopped and then as the IGN SWis turned from the ON position to the ACC position at t1 as shown in theleft end of FIG. 3, the FI-ECU 33 is switched to the engine disablingmode. When the door SW is shifted from the OFF position (door closed) tothe ON position (door opening) at t2 in the door unlock mode, it isjudged that the driver is about to disembark and the transmission of a Bsmall response demand signal (e.g. of 300 kHz having substantially a0.5-meter-radius communication area denoted by B (small) in FIG. 13) isthen commenced. This is followed by transmitting the B small responsedemand signal at equal intervals of the second predetermined time (xseconds) from the vehicle. Then, as the door SW is shifted from the ONposition to the OFF position (door closed) at t3, the I response demandsignal is transmitted at the predetermined intervals.

[0087] When the entry key is disembarked, it enables to receive not theI response demand signal but the B small response demand signal. Then aresponse signal to the B small response demand signal including the Bcode is released. When the response signal including the B code isreceive and is judged to be valid at t4, the A response demand signal iscommenced to be transmitted while the transmission of the I responsedemand signal is stopped. The entry key continues to release the A and Bcodes while receiving both the A and B small response demand signals.

[0088] As the driver with the entry key moves away from the vehicle andsteps out from the B small area shown in FIG. 13, it is disabled toreceive the B small response demand signal and no response signal with Bcode to the B response demand signal shall be sent back. When the B codeis not received by the vehicle after a predetermined period from thereception of the A code (at t5 in FIG. 3), the B response demand signalis switched from the B small signal to the B large signal. As the B codeis no more received after the predetermined period while the A code isreceived and its welcome code examination is executed (i.e. in thisembodiment, only the A code is continuously received but the B code hasnot been received in y seconds), the door is then locked at t7 when thefinal A code is examined to be valid.

[0089] After t8 when the setting (m seconds) of the T-OUT timer haselapsed since the entry key is far enough away from the vehicle not toreceive the A response demand signal and thus not to send back the Acode, the intermittent transmission of only the A response demand signalat the intervals of y seconds is maintained. Alternatively, as denotedby the dotted line in FIG. 3, the door may be locked at t5 when the Acode is received just after the reception of the B code at the estimatedmoment is not executed.

[0090] The operation of the smart entry unit 1 will now be describedschematically referring to the flowcharts of FIGS. 4 and 5.

[0091] Upon energized, the system is initialized in its entirety (StepS1). At Step S2, it is examined whether the ignition switch (referred toan IGN SW hereinafter) is turned on or not. When the IGN SW is turnedoff by the driver to stop the vehicle at t1 in FIG. 3, the proceduregoes to Step S3 where the refresh 1 process, i.e. the initialization offlags for the (anti-thief) immobilizing system, is carried out. Thisprocess at Step S3 will be explained later in more detail referring toFIG. 7.

[0092] This is followed by Step S5 where it is examined whether the dooris unlocked or not. At Step S6, it is examined whether or not the doorSW is turned from the ON position to the OFF position (i.e. whether theopened door of the vehicle is closed or not). As it is judged “NO” atStep S6 while the door is opened for disembarkation, the procedure jumpsto Step S9 where it is examined whether or not the manual SW7 a isturned on for shifting the system to the manual mode where the door canbe unlocked and locked using the manual switch. In normal, the manual SW7 a remains turned off (i.e. the manual mode is not selected) and it isjudged “NO”. It is then examined at Step S10 whether or not the door SWis turned from the OFF position to the ON position (i.e. the closed dooris opened).

[0093] As the door is opened for disembarkation, the door switch isturned from the OFF position to the ON position and it is judged “YES”at Step S10. Then, Step S11 follows where it is examined whether theBREC flag is 1 or not (i.e. the B code is received or not). In thebeginning, the B code is not received and the procedure advances to StepS12 where the BSTM flag is set to 1 and the variable n for determiningthe type of the response demand signal (A, B small, or B large) is resetto 0.

[0094] Step S12 is a process of selecting the type of the responsedemand signal to be transmitted and, as will be explained later, the Bsmall type having a smaller communication area is set. At Step S13, thetimer interruption permitting bit for enabling the transmission of theresponse demand signal is set, i.e. the transmission of the responsedemand signal by timer interruption is enabled.

[0095] Then Step S14 follows where it is examined whether the valid IDcode is received or not. When it is affirmative, it is then judged atStep S15 what the function code is. More specifically, it is examinedwhether received signal is the response signal (A code or B code) fromthe entry key 50 or the manual code for the manual operation. In thebeginning, it is judged “NO” at Step S14 and the procedure moves to StepS15A where it is examined based on the IMCHK flag whether theimmobilizing checkup is finished or not. At the time, the immobilizingcheckup is not performed and the procedure jumps to Step S30 (in FIG.5). Similarly, it is judged “NO” at Step S30 and the procedure goes toBlock S41. At Block S41, the flags for the welcome function areinitialized when the code is not received during a predetermined periodof time.

[0096] In fact, it is examined referring to the OUT flag at Step S31whether or not the entry key is out of the communication area for the Aresponse demand signal. In the beginning, it is not registered (i.e. OUTflag=0) that the entry key is out of the communication area for the Aresponse demand signal. It is then examined at Step S32 whether the RCHKflag is 1 or not (i.e. the T-OUT timer for setting time duration todetermine that the entry key is not adjacent to the vehicle, has beenstarted or not) When it is judged “NO”, the procedure goes to Step S33where the T-OUT timer is set to m seconds. It is preferable that msatisfies m sec>y(=3x) sec≧z sec where y is the interval of transmission(or cycle) of the A response demand signal, x is the interval oftransmission of the B response demand signal, and z is the interval oftransmission of the I (immobilizing) response demand signal, as shown inFIG. 2. Then, at Step S34, the RCHK flag is set to 1 for starting theT-OUT timer.

[0097] This is followed by Step S35 where it is examined whether theT-OUT timer is turned to zero as the setting time of m seconds has beenelapsed. In the beginning, the setting time of m seconds is not elapsedand thus the procedure returns back to Step S2.

[0098] As the driver disembarks and the door is closed, the door switchis shifted from the ON position to the OFF position allowing Step S6 tojudge “YES”. The procedure thus goes to Step S7 where the refresh 1 flagis reset to 0. Step S8 follows where the timer interruption permittingbit for permitting the transmission of the I response demand signal isinitiated to enable the transmission of the I response demand signalwith timer interruption. Then, the procedure moves to Steps S14, S15A,and S30, and Block S41 and returns back to Step S2.

[0099] As the entry key 50 is moved out of the vehicle, it receives theB small response demand signal and sends back the B code. The B codefrom the entry key 50 is received by the receiver on the vehicle andqualified as a valid code and it is then judged “YES” at Step S14. Theprocedure thus goes to Step S15 where it is examined whether or not thesignal code received is the manual code sent from the entry key 50 bythe manual switch operation for locking and unlocking the door. When itis judged “YES”, the procedure advances to Step S16 where the manualoperation is enabled (which is a process to interpret the code issuedthrough the manual switch operation and will be explained in no moredetail).

[0100] As the received code is the B code carried on a response signalto the response demand signal at present, it is judged “NO” at Step S15and the procedure moves to Step S17 where it is examined whether themanual SW is turned on or not. When it is judged “YES” at Step S17, theprocedure returns back to Step S2. As “NO” is given at Step S17,however, the procedure goes to Step S18 where the welcome functionprocess for unlocking and locking the door in response to the result ofthe welcome code judgment is executed.

[0101] Welcome Function Process at Disembarkation

[0102] The welcome process at Step S18 in FIG. 4 will now be explainedin more detail referring to FIGS. 9 and 10. It is assumed that thedriver stops the engine, disembarks, and departs with the entry key fromthe vehicle. As described previously, the disembarkation of the driveris followed by Step S12 (FIG. 4) for selecting the transmission of the Bsmall response demand signal and resetting the variable n to 0 and StepS13 for enabling the transmission of the B response demand signal withtimer interruption. Then, the welcome process is commenced at Step S18in response to the reception of the correct B code.

[0103] The welcome process starts with Step S171 where it is examinedwhether the signal code received from the entry key is the A code ornot. In the beginning, since the A response demand signal is nottransmitted it is judged “NO”, allowing the procedure to goes to StepS201. When it is judged at Step S201 that the received code coincideswith the right B code, the procedure moves to Step S202 where the BRECflag representing the reception of the B code is set to 1 while thenumber of consecutive receptions of the A code denoted by I is set tozero. Step S204 follows where the door is unlocked.

[0104] It is then examined at Step S209 whether the AREC flag is 1 ornot. As the A code is not received by now, it is judged “NO”. Theprocedure hence goes to Step S210 where the ATM flag is set to 1 forenabling the intermittent transmission of the A response demand signal.At Step S211, the variable n is set to 0. At Step S212, the timerinterruption permitting bit for the I response demand signal is clearedoff to inhibit the transmission of the I response demand signal. At StepS214, the BCHG flag is set to 0. While the B code only is receivedcontinuously, the above steps are repeated.

[0105] When the A code is released from the entry key in response to thereception of the A response demand signal and received by the vehicle,it is judged “YES” at Step S171. The procedure then goes to Step S172where the AREC flag is set to 1 while the OUT flag and the RCHK flag areturned to 0 to register that the entry key 50 is within thecommunication area for the A response demand signal and reset the T-OUTtimer. At next Step S173, the variable I indicating the number ofconsecutive reception of the A code is increased by 1 for updating (I isthus turned to 1). It is then examined at Step S174 whether or not thevariable I is turned to 2 (for example). In the beginning, I is not 2and the procedure jumps to Step S180.

[0106] It is examined at Step S180 whether the BSTM flag indicating theselection of the B small response demand signal is 1 or not. As the BSTMflag is 1 so far, it is judged “YES” and the procedure moves to StepS181 where it is examined whether the BCHG flag for causing the Bresponse demand signal being switched from the B small to the B large is1 or not. As the BCHG flag is now 0, the procedure goes to Step S182 forsetting the BCHG timer to, for example, 30 seconds.

[0107] The setting time for the BCHG timer may be determined on thebasis of experiments or actual measurements to a duration enough toallow the entry key to get away enough from the vehicle and step out ofthe communication area for the B large response demand signal. Then, theprocedure moves to Step S184 where the BCHG flag is shifted to 1. It isthen examined at Step S185 whether the BCHG timer is turned to zero ornot. In the beginning, the timer is not zero and the procedure returnsback to Step S2.

[0108] As the entry key steps out of the communication area for the Bsmall response demand signal (FIG. 13), the B code is no more receivedbut the A code is continuously received on the vehicle. Step S171 onlyof the welcome process repeats judging “YES”. Accordingly, the variableI is updated to 2 at Step S173 and it is judged “YES” at Step S174. Theprocedure hence goes to Step S176 for locking the door.

[0109] When the A code is next received from the entry key, theprocedure jumps from S174 to S180 and then from S181 to S185. As it isjudged “NO” at Step S185 before the setting time (for example, 30seconds) of the BCHG timer elapses, the procedure returns back to StepS2. When the setting time has elapsed, however, it is judged “YES” atStep S185.

[0110] As a result, the procedure advances to Step S186 where the BSTMflag for selecting the B small response demand signal is turned to 0. AtStep S187, the BLTM flag for selecting the B large response demandsignal is turned to 1. Accordingly, the transmission of the B largeresponse demand signal is initiated by timer interruption. As the entrykey is far enough away the vehicle and out of the communication area ofthe B large demand signal at the time, it is disabled to receive the Blarge response demand signal and sends back non of the B code.

[0111] As the entry key departs further from the vehicle, it is disabledto receive finally the A response demand signal and thus to release theA code. This causes Step S14 of the procedure to judge “NO” and theprocedure moves via Step S15A shown in FIG. 4 to Step S30 shown in FIG.5. Then, Block S41 follows in which the flags are examined at Steps S31and S32 before the T-OUT timer is set to m seconds at Step S33, asdescribed previously. As long as it is judged “NO” at Step S35, theprocedure always restarts from Step S2.

[0112] When the A code is no more sent back and it is thus judged “YES”at Step S35 after m seconds of the setting time on the T-OUT timer, i.e.any sent-back code from the entry key 50 is not received in a durationof m seconds, as illustrated in the flowchart of FIG. 5, the proceduremoves to Steps S36 to S39 for initializing the AREC, BREC, BLTM, andBSTM flags to 0 which flags relate to the welcome process. The procedurethen goes to Step S40 where the OUT flag is turned to 1 to register thatthe entry key 50 is out of the communication area for the A responsedemand signal. This is followed by the procedure returning back to StepS2 for repeating the steps.

[0113] As the BLTM and BSTM flags are set to 0 at the time, theprocedure is after t8 in FIG. 3 and before t1 in FIG. 2 where theintermittent transmission of only the A response demand signal isexecuted. As apparent, the A response demand signal is not received bythe entry key and its response signal carrying the A code is not sentback.

[0114] Welcome Function Process at Embarkation

[0115] A case of the driver with the entry key 50 approaching andembarking the vehicle will now be explained. As the entry key moves froma far enough point where the A response demand signal cannot be receivedto a near point within the communication area for the A response demandsignal, it receives the A response demand signal and sends back the Acode in response. When the A code is received by the vehicle, it isjudged “YES” at Step S14 and the procedure goes to Step S15 for judgmentwhether the received code is the manual code or not.

[0116] When the judgment is affirmative, the procedure advances to StepS16 for executing the manual operation process. The received code is notassumed now to be the manual code and it is thus judged “NO” at StepS15. The procedure then moves to Step S17 where it is examined whetherthe manual SW is turned on or not. When so, the procedure returns backto Step S2. But it is now judged “NO” and the procedure goes to Step S18for initiating the welcome process shown in FIG. 9.

[0117] In the welcome process, “YES” at Step S171 and “NO” at Step S174are provided and the procedure jumps to Step S180. As “NO” is also givenat Step S180, it is examined at Step S188 whether the BLTM flag is 1 ornot. At the time, the BLTM flag is not 1 and procedure moves to StepS189 where the BLTM flag is shifted to 1 to select the transmission ofthe B large response demand signal. Then at Step S190, the variable n isset to 1. While only the A code is received from the entry key, theabove steps are repeated (excepting that because “YES” is given at StepS188, Steps S189 and S190 are skipped). The A response demand signal andthe B large response demand signal are thus transmitted at theirrespective intervals of time.

[0118] As the driver steps closer to the vehicle, the entry key isenabled to receive the B large response demand signal from the vehicleand send back the B code. When the B code is received by the vehicle, itis judged “NO” at Step S171 but “YES” at Step S201. Accordingly, thedoor is unlocked at Step S204. As the A code has been received at thattime, “YES” is given at Step S209 and the transmission of the I responsedemand signal is inhibited at Step S212. At next Step S214, the BCHGflag is shifted to 0 to inhibit the switching of the response demandsignal from the B large to the B small.

[0119] As the driver opens the door, steps in the vehicle, and closesthe door, it is judged “YES” at Step S6 (FIG. 4). Then, the timerinterruption permitting bit for permitting the transmission of the Iresponse demand signal is enabled at Step S8 to permit the timerinterrupted intermittent transmission of the I response demand signal.At the time, the entry key is disabled to receive the A and B responsedemand signals (which are transmitted to only the outside of thevehicle) and hence, none of the A code and the B code are received bythe vehicle.

[0120] The entry key 50 receives the I response demand signal andresponds to send back the I code. When the I code is received by thevehicle, the procedure runs through Steps S14, S15, and S17 and entersat Step S18 the welcome process shown in FIG. 9. As it is judged “NO” atboth Steps S171 and 201, the procedure advances to Step S221 shown inFIG. 10. A block denoted by the chained line SC in FIG. 10 is a knownimmobilizing process.

[0121] It is examined at Step S221 whether the IMDONE flag indicatingthe completion of the immobilizing checkup is 1 or not. At the time, theimmobilizing checkup is not executed and the procedure goes to Step S222for executing the immobilizing checkup. In the immobilizing checkup, theI code received is examined whether it is valid or not as will beexplained later referring to FIG. 11. When so, the IMOK flag is turnedto 1. Step S223 follows where the immobilizing checkup result isexamined based on the IMOK flag whether or not it is all right.

[0122] When it is judged “NO” at Step S223, the operation of the engineis disabled at Step S227. When it is “YES”, the procedure goes to StepS224 for permitting the start of the engine. At Step S225, the ATM flagis shifted to 0 and at Step S226, the AREC flag is shifted to 0. In thenext cycle of receiving the I code, it is judged “YES” at Step S221. Theprocedure then moves to Step S228 where the timer interruptionpermitting bit for the I response demand signal is cleared off toprohibit the intermittent transmission of the I response demand signal.

[0123] The bit information of the IMOK flag is transferred via thecommunication line (bus) 32 to the FI-ECU 33 (See FIG. 1). In responseto the bit of the IMOK flag, the FI-ECU 33 controls the action of a fuelpump, a fuel injector, a fuel feeder, and an ignition device (each notshown) in any known manner so that when the bit is 1, the engine isenabled and while when 0, the engine is disabled.

[0124] The blocks enclosed with the chain line SB in FIG. 9 are providedfor assigning different levels of hysteresis to the communication areafor the B response demand signals at the embarkation and thedisembarkation, and selecting the B small response demand signal whenthe driver gets away from the vehicle for permitting the door locking atearlier timing and while the B large response demand signal when thedriver approaches towards the vehicle for permitting the door unlockingat possibly earlier timing. It would hence be appreciated that when thehysteresis is not applied, the blocks for switching between the B smallsignal and the B large signal is unnecessary.

[0125] When the driver embarks and the IGN SW is turned on, it is judged“YES” at Step S2 in FIG. 4 and the procedure moves to Step S21 where arefresh 2 process for initializing the welcome function flags is executedas will be explained lately in more detail referring to FIG. 8. It isthen examined at Step S22 whether the IMOK flag is 1 or not (i.e. theresult of the immobilizing checkup is all right or not).

[0126] If it is judged “NO” at Step S22, the procedure goes to Step S24for disabling the operation of the engine.

[0127] It is then examined at Step S25 whether the IMDONE flag is 1 ornot (i.e. the immobilizing checkup is finished or not). When judged“NO”, the procedure moves to Step S26 where the timer interruptionpermitting bit for permitting the transmission of the I response demandsignal is enabled similar to Step S8. Then, the immobilizing checkupprocess explained later in conjunction with FIG. 11 is executed at StepS27. The procedure goes from Step S2 to Step S22 thereafter. In theimmobilizing checkup process, when the immobilizing code received by thevehicle is qualified to be judged that its key operation is correct, theIMOK flag is shifted to 1. It is hence judged “YES” at Step S22.

[0128] By now, the checkup is right and the procedure advances to StepS23 for enabling the start of the engine. As the IMDONE flag is set to 1in the immoblizing checkup process mentioned above, “YES” is given atStep S25. The procedure then goes to Step S28 where the timerinterruption permitting bit for the I response demand signal is clearedoff to prohibit the transmission of the I response demand signal. Duringthe running of the vehicle, the IGN SW remains turned on, the abovesteps are repeated.

[0129] When the IGN SW is turned to the ACC or OFF position to stop theengine, it is judged “NO” at Step S2. The procedure then moves to StepS3 for executing the above described process at the disembarkation.

[0130] The transmission of the response demand signals in the welcomeprocess will be explained referring to FIG. 6. This process is executedin every x seconds by the timer interruption to intermittently transmitthe A or B (B large or B small) response demand signal, provided thatthe response demand signal transmission selecting flag is 1. The A, Blarge, and B small response demand signals may be selected as previouslydescribed referring to FIGS. 2, 3, and 13.

[0131] The procedure starts with Step S91 for examining whether MOD(n,3)is zero or not. MOD(n,3) is the remainder of the variable n divided by3, which n is described previously concerning with Steps S190 and S211.When MOD(n,3) is zero, the procedure goes to Step S92 where it isexamined whether the ATM flag is 1 or not. When so, the procedure goesto Step S93 for permitting the transmission of the A response demandsignal.

[0132] When the remainder of n/3 is 1 or 2, it is judged “NO” at StepsS91 or S92 and the procedure moves to Step S94 where the BTSM flag isexamined whether it is 1 or not. When so, the procedure goes to Step S95for permitting the transmission of the B small response demand signal.When judged “NO” at Step S94, the procedure moves to Steps S96 forexamining whether the BLTM flag is 1 or not. When so, the procedureadvances to Step S97 for permitting the transmission of the B largeresponse demand signal.

[0133] The refresh 1 process at Step S3 (FIG. 4) will now be explainedreferring to FIG. 7. At Step S101, the RF1 (refresh 1) flag is examinedwhether or not it is 1 as indicating that the refresh 1 process iscompleted. When judges “YES”, i.e. the refresh 1 process is completed,the procedure jumps to EXIT. In the beginning, it is judged “NO”. Atnext Step S103, the IMOK flag is shifted to 0 and at Step S104, theIMDONE flag (immobilizing checkup is done) is shifted to 0. At StepS105, the IMCHK flag (immobilizing checkup is started) is reset to 0.

[0134] As the result, the initialization of the immobilizing checkupflags is completed. At Step S109, the RF1 flag is turned to 1 toregister that the refresh 1 process has been done. At Step S110, the RF2flag is turned to 0 to register that the refresh 2 process is not yetdone.

[0135] The refresh 2 process at Step S21 (FIG. 4) will be explained inmore detail referring to FIG. 8. At Step S121, the RF2 flag is examinedwhether it is 1 or not, i.e. the refresh 2 process has been done or not.When “YES”, the procedure jumps to EXIT. When judged “NO”, the procedureruns through Steps S122, S123, and S124 for resetting the ATM, BLTM, andBSTM flags to 0, respectively. Those steps are to inhibit thetransmission of the A, B large, and B small response demand signals,respectively.

[0136] This is followed by Steps S125 and S126 for resetting the ARECand BREC flags to 0, respectively. These two steps are provided forregistering that the code, which is included in a response signal sendback from the entry key 50 in response to the reception of the demandsignal transmitted from the vehicle, is not yet received by the receiveron the vehicle. At Step S128, the variable n for determining theresponse demand signal to be transmitted is turned to zero.

[0137] At Step S129, the OUT flag is shifted to 0 (denied) forindicating that the entry key 50 is out of the communication area of theA response demand signal. At Step S130, the RCHK flag is set to 0 toindicate that the T-OUT timer is not started which sets the limited timefor detecting whether or not the entry key 50 is out of thecommunication area for the A response demand signal. At Step S131, thetimer interruption permitting bit for the response demand signal iscleared off to inhibit the timer interrupted transmission.

[0138] After the above steps, the initialization of the welcome functionflags are completed. Then, Step S135 follows where the RF2 flag isturned to 1 to register the completion of the refresh 2 process. At StepS136, the RF1 flag is reset to 0 for registering the non-completion ofthe refresh 1 process.

[0139] The immobilizing checkup process at Step S222 (FIG. 10) will beexplained in more detail referring to FIG. 11. The immobilizing checkupprocess starts with Step S230 for examining whether the IMCHK flag forindicating the starting of the immobilizing checkup process is 1 or not.When the immobilizing checkup process is not started and “NO” is given,the procedure moves to Step S235 for setting the immobilizing checkuptimer T-IMCHK to a desired immobilizing checkup period (for example, 30seconds). At Step S236, the IMCHK flag is shifted to 1.

[0140] When the immobilizing checkup process has been started and it isjudged “YES” at Step S230, the procedure advances to Step S231 forexamining whether or not the immobilizing code I sent back from theentry key is identical to the code previously saved in a memory on thevehicle. When so, the procedure goes to Step S232 where the IMOK flag isturned to 1 to indicate the confirmation of the immobilizing codecomparison and Step S233 follows. Those steps allow the FI-ECU 33 topositively control the operation of the engine as described previously.

[0141] When judged “NO” at Step S231, the procedure goes to Step S246for examining whether the IMCHK timer is timed up or not. When not, theimmobilizing checkup process is terminated. When judged “YES” at StepS246, the procedure goes to Step S233. At Step S233, the IMDONE flagindicating that the immobilizing checkup process has been done is turnedto 1.

[0142]FIG. 12 illustrates the intermittent transmission of the Iresponse demand signal with the timer interruption permitting bit forthe I response demand signal being enabled, where the timer interruptionmay be carried out in every z seconds. The procedure starts with StepS271 for examining based on the IMDONE flag whether the immobilizingcheckup process is done or not. If not, the procedure goes to Step S272for permitting the transmission of the I response demand signal. Whenthe immobilizing checkup process has been done and it is judged “YES” atStep S271, the procedure is terminated.

[0143] According to the embodiment mentioned above, only when the entrykey sends back a signal in response to reception of the A responsedemand signal transmitted from the vehicle at longer intervals in thewider communication area, and the signal thus sent back is received bythe receiver on the vehicle and confirmed to be correct response signalthrough the welcome code examination, the B response demand signal forthe smaller communication area is transmitted at least once in theperiod of transmitting two of the A response demand signals. In otherwords, even if any other person or object not carrying the entry key andunrelated to the vehicle moves into the A (response demand signalcommunication) area shown in FIG. 13, the transmission of the B responsedemand signal is not executed.

[0144] Accordingly, the occasion of transmitting the B response demandsignal for actually controlling the unlocking and locking action of thedoor is minimized, hence decreasing the power consumption of the vehiclebattery. Also, the interval between transmitting timings of two responsedemand signals is significantly minimized, thus allowing the position ofthe entry key relative to the vehicle to be more accurately identified.As a result, the transmission of the B response demand signal atintervals of an optimum period and in an optimum or relatively smallersize of the communication area can be executed without largelyincreasing the power consumption thus to precisely control the vehiclemounted components, for example, the automatic unlocking and lockingaction of the door of the vehicle, corresponding to the distance betweenthe entry key and the vehicle. More particularly, the precise controlover the vehicle mounted components with the entry key can successfullybe conducted in compatibility with the favorable energy saving.

[0145] The foregoing embodiment is based on the use of the B responsedemand signals common to all the doors of a vehicle in conjunction withtheir response signals. In that case, it may happen that when the entrykey steps in such a predetermined communication area as denoted by the B(large) in FIG. 13, all the doors are unlocked at same time.

[0146] For avoiding such an event, an alternative embodiment is providedas shown in the schematic view of FIG. 14 where three different Bresponse demand signals B1, B2, and B3 respectively assigned to two ofleft and right doors 2 a, 2 b and a rear trunk door 2 c are provided.For example, when any one of the three B response demand signals is notreceived, all the doors are locked simultaneously. On the other hand,desired one of the doors can be unlocked by the controlling action of avehicle mounted receiver which receives a B code for the desired doorincluded in a response signal to the B response demand signal assignedto the desired door.

[0147] It should be understood by those skilled in the art that forapplying the B response demand signals assigned to their respectivedoors, Step S201 in the flowchart of the welcome process shown in FIG. 9may be modified to examine the received code for its matching with anunique code assigned to the desired door. Hence, the modification of theflowchart will be explained in no more detail. It is also appreciatedthat different levels of the hysteresis may be allocated to the sizes ofthe communication areas between the unlock and lock operation.

[0148]FIG. 15 illustrates an exemplary format of the response signalapplicable to the above- and under-mentioned embodiments of the presentinvention. As shown, CDA is a start bit, CDB is an identification code,CDID is an ID code uniquely assigned to each vehicle, and CDF is afunction code. The figures in the parenthesis represent the numbers ofbits of the codes. In general, the ID code is used for examining if anentry key is authentic, while the function code is for discriminatingthe A and B codes from each other. The function code may be comprised offour bits, respectively; for example, the A code is [1000], the B code[1001], the manual lock code [1100], and the manual unlock code [1101],respectively in the case of FIG. 13, while the A code is [1000], the Bcode for the driver's door [1001],the B code for the passenger's door[1010], and the B code for the trunk door [1011] in the case of FIG. 14.

[0149]FIG. 16 illustrates an exemplary format of the response signal forthe (anti-thief) immobilizing function applicable to the embodiments ofthe present invention. As the code comparison for the immobilizingfunction is extremely important for ensuring the anti-thief action aswell known, it may preferably be differentiated in the structure fromthe other codes. As shown, CDA is a start bit, CDB is an identificationcode, and CDIM is an immobilizing function ID code. It is also possibleto have all types of the response signals designed to a singleparticularly structured format.

[0150] Although the hysteresis characteristic is assigned to thecommunication areas for the B response demand signal between the unlockmode and the lock mode, the present invention is not limited to alwayshave the hysteresis characteristics. The B large response demand signaland the B small response demand signal shown in the schematic view ofFIG. 13 and the timing charts of FIGS. 2 and 3 may be a single andcommon B response demand signal.

[0151] As for a further embodiment of the present invention using thesingle and common B response demand signal, a flowchart of its mainprocedure (corresponding to FIGS. 4 and 5) is shown in FIGS. 17 and 18while a flowchart of its welcome function process (corresponding to FIG.9) is shown in FIG. 19. Throughout the figures, like components aredenoted by like numerals as those shown in FIGS. 4, 5, and 9 and will beexplained in no more detail but only different steps or blocks will beexplained below.

[0152] At Step S12B in FIG. 17, the B response demand signal selectingflag BTM is shifted to 1 for enabling the timer interrupted transmissionof the B response demand signal. At Step S38B in FIG. 18, the flag BTMis reset to 0 to inhibit the transmission of the B response demandsignal. Step S186B in FIG. 19 is provided for examining whether the flagBTM is 0 or not. The flag BTM is turned to 1 at Step S188B to permit thetransmission of the B response demand signal, preparing for unlocking ofthe door as the driver comes towards the vehicle. When the entry keydeparts further from the vehicle and it is disabled to receive even theA response demand signal, the intermittent transmission of the Aresponse demand signal only is maintained as described with the previousembodiment.

[0153] As the entry key 50 comes close to the vehicle, it receives the Aresponse demand signal and sends back the A code. When the A code isreceived by the vehicle mounted receiver, it is judged “YES” at StepS171, “NO” at Step S174, and “YES” at Step S186B similar to those of theprevious embodiment. Accordingly, Step S188B permits the transmission ofthe B response demand signal. The succeeding procedure may clearly beunderstood from the forgoing descriptions.

[0154]FIG. 20 is a flowchart showing the timer interrupted transmissionof the A and B response demand signals executed in the welcome processof this embodiment. This drawing is similar to FIG. 6 in which likeblocks are denoted by like numerals as those shown in FIG. 6 and theywill be explained in no more detail. It is examined at Step S91B whetherMOD(n, 2) which is the remainder of n/2 is zero or not (i.e. n is an oddnumber or an even number). When judged “NO” or n is an odd number, theprocedure goes to Step S94B for examining whether the flag BTM forpermitting the timer interrupted transmission of the B response demandsignal is shifted to 1 or not.

[0155] When so, the transmission of the B response demand signal ispermitted at Step S95B and procedure moves to Step S98. When it isjudged“NO” at Step S94B, n is updated at Step S98 before the procedureof this process is terminated. The divisor such as 2 or 3 used at StepsS91B and S91 may preferably be determined so that the transmission ofthe response demand signals is timed favorably with the interval of thetimer interruption settings (x or x′ seconds).

[0156] Although the response demand signal transmitted from the vehiclemounted receiver is classified into two different types, A and B, forthe wider and the narrower communication areas respectively in theprevious embodiments, the prevent invention may employ three or moretypes of the response demand signals for different sized communicationareas. FIGS. 21A and 21B are timing charts illustrating the transmissionof three different types of the response demand signal.

[0157] As shown, while the A response demand signal for the widestcommunication area is transmitted at intervals of the longest period y,the B response demand signal for the second widest communication area istransmitted, for example, at every intermediate moment between twoadjacent transmitting timings of the A response demand signal, providedthat the A code is received by the vehicle, indicating that the Aresponse demand signal is successfully received by the entry key whichis moving towards the vehicle.

[0158] The C response demand signal for the smallest communication areais also transmitted at every intermediate moment between the A responsedemand signal and the B response demand signal, provided that the B codeis received indicating that the B response demand signal is successfullyreceived by the entry key which is moving towards the vehicle. Thosecodes in the response signals may be expressed as, for example, the Acode [1000], the B code [1001], the C code [1011] and the I code [0101].

[0159] On the other hand, when the driver disembarks and the entry keydeparts from the vehicle, the response signal responding to the Cresponse demand signal for the smallest communication area will firstbecome impossible of being received, then the response signal to the Bresponse demand signal for the medium sized communication area, andfinally the response signal to the A response demand signal for thewidest communication area. The interval between two adjacent receptionsof the response signals will thus be increased step by step.

[0160] In this embodiment, the response signal carrying the responsecode (one of the A, B, and C codes) is send back from the portabletransmitter/receiver of the entry key corresponding to which one of theresponse demand signals for the communication areas of different sizesis received by it, hence allowing the control unit on the vehicle tointimately identify the location of the entry key relative to thevehicle. Accordingly, the vehicle mounted components can favorably becontrolled depending on the distance from the vehicle to the entry keydetermined on the basis of the code in the response signal sent back.

[0161] As will be understood from the timing chart of FIGS. 21A and 21B,the response codes are received at intervals of a shorter period or at ahigher rate of frequency from the entry key which is in a positioncloser to the vehicle. The location of the entry key relative to thevehicle can thus be identified by measuring the receiving cycle orfrequency of the response codes on the vehicle. Also, as the entry keyis in the position closer to the vehicle, the receiving cycle will beexpected to be shorter thus possibly making the response action of thevehicle mounted components quicker.

[0162] Although the above-mentioned embodiments include transmittingfrom the vehicle mounted transmitter different types of the responsedemand signals which are different in the size of the communication areaand the characteristics, sending back from the entry key the responsecodes corresponding to the type or the communication area of theresponse demand signal received, and identifying on the basis of thereceived response code the location of the entry key relative to thevehicle, the different types of the response demand signals may bedesigned uniformly in the characteristics and their response codes forsimplification of the signal structure, when they are transmitted fromthe vehicle mounted transmitter at their respective frequencies orrepetitive cycles different each other in their corresponding sizes ofthe communication areas as shown in FIGS. 21A and 21B.

[0163] Subsequently, the distance of the entry key from the vehicle cansuccessfully be identified from the receiving intervals, thefrequencies, or repetitive cycles of the response signal (response code)received by the vehicle mounted receiver and used for favorablycontrolling the operation of the vehicle mounted components according tothe distance identified. An embodiment of the above modification willnow be described referring to FIGS. 22 and 23. In these two graphs, theheight of the different types of the response demand signals WS and WLrepresents only the intensity of the signal which is the size of thecorresponding communication area.

[0164]FIG. 22 is a time chart showing schematically the actions when thedriver carrying the entry key disembarks and walks away from thevehicle. As the vehicle 1 stops, the IGN SW is turned at t1 from the ONposition to the ACC position and the door is opened at t2 by the driverfor disembarkation. Then, the door SW is shifted from the OFF (open)position to the ON (close) position. This triggers the transmission ofthe W small response demand signal WS for a narrow communication area.The W small response demand signal WS is transmitted from the vehiclemounted transmitter at the predetermined intervals of 2 u.

[0165] When the entry key 50 steps out from the vehicle and is enabledto receive the W small response demand signal WS, it releases a responsesignal carrying the W code (referred to as W code hereinafter) As the Wcode is received and the welcome code comparison is confirmed at t3, afirst timer TWR1 for the receiving interval is set to a period v andthen initiated. Simultaneously, the intermittent transmission of the Wlarge response demand signal WL is initiated, of which the communicationarea is greater than that of the W small response demand signal (i.e.the transmitting output is higher while the other characteristics areidentical to WL).

[0166] In this embodiment, the W large response demand signal WL istransmitted at every intermediate moment between two transmittingtimings of the W small response demand signal WL and hence at theintervals equal to 2 u seconds as illustrated. The setting time v of thetimer may preferably be equal to the minimum transmitting interval (u)between the adjacent two response demand signals WS and WL.

[0167] This setting is preferable but not necessary. It is simplyrequired to transmit the two response demand signals WS and WLalternately and more generally, to clearly discriminate the differencebetween an interval of transmitting timings when only the W largeresponse demand signal WL is transmitted and the other interval whenboth of the W large and small response demand signal WL and WS aretransmitted (preferably, the latter is shorter). In practice, thesetting time v may preferably be set to (u+Δu) seconds consideringvarious unevenness in the system.

[0168] As the welcome code comparison is confirmed at t4 with the W codereceived, a second timer TWR2 for the receiving interval is set to v andinitiated. Simultaneously, it is examined whether the first timer TWR1is timed up or not. As apparent from the criteria for setting the twotimers, the two timers are not timed up while the W large and smallresponse demand signal WL and WS are successfully received by the entrykey which in turn releases their corresponding response signals W.

[0169] As the entry key 50 departs further from the vehicle and receivesno more the W small signal WS, the vehicle mounted receiver is disabledto receive its response signal. One of the timers TWR (namely, thesecond timer TWR2 in this case) is then timed up to be turned to zero att5. As the W code responding to the W large response demand signal isreceived and the welcome code comparison is confirmed at t6, the firsttimer TWR1 is restarted and the time up of the second timer TWR2 isacknowledged.

[0170] It is hence determined that the receiving interval of the W codeis longer than v, i.e. the entry key is out of the communication area ofthe W small response demand signal WS, allowing the door of the vehicleto be locked. When the W code is not received within m seconds of thepreset time after the locking action, the transmission of the W smallresponse demand signal WS is stopped and the intermittent transmissionof only the W large response demand signal WL is continued.

[0171] Referring to FIG. 23, the actions when the driver comes towardsthe vehicle 1 and its location is detected will be explained. When theentry key is out of and significantly distanced from the vehicle withthe door locked in its disembarkation or parking mode, the W largeresponse demand signal WL for the wider communication area is beingtransmitted at the predetermined intervals (of 2 u seconds) from thevehicle as described previously and shown at the left most portion inFIG. 23. As the driver carrying the entry key steps into thecommunication area of the W large response demand signal WL about thevehicle, the entry key receives the W large response demand signal WL att1.

[0172] Then, the entry key send back the W code responding to thereception of the W large response demand signal WL. As the W code isreceived by the vehicle and determined at t2 by the welcome codecomparison that it is valid, the vehicle mounted control unit starts thefirst timer TWR1 for the receiving interval and simultaneously transmitsthe W small response demand signal WS at the equal interval (of 2 u) andat every intermediate moment between two adjacent transmitting timingsof the W large response demand signal WL.

[0173] When the W code which is released from the entry key respondingto reception of the W large response demand signal at t3 prior to thereception of the W small response demand signal WS is received andjudged by the welcome code comparison that it is valid, the second timerTWR 2 for the receiving interval is started. At the time, the firsttimer TWR1 is timed up and the door is not unlocked.

[0174] As the entry key 50 comes close enough to receive the W smallresponse demand signal WS, it releases the corresponding W code. Uponthe W code received and judged that it is valid, the second timer TWR2is started at t4 and it is determined that the first timer TWRL is nottimed up. Then, the door of the vehicle is unlocked. When the door isopened (the door SW turned on) and then closed at t5, it is determinedthat the driver is in the vehicle. Then, the transmission of the I(immobilizing) response demand signal is initiated for its communicationarea limited within the vehicle (not shown in FIG. 23).

[0175] As the entry key releases the immobilizing code (I code) inresponse to the I response demand signal, the immobilizing code isreceived and examined by the vehicle. When it is judged that the I codeis valid, the transmission of the I response demand signal is stoppedthus enabling the start of the engine. As the ignition SW is turned tothe ON position at t6, the transmission of both the response demandsignals WL and WS is stopped and simultaneously the refresh 2 process isinitiated as will be explained later.

[0176] The transmission of the response demand signals WL and WS may bestopped when it is judged that the I code is valid. The response demandsignal is not limited to the two types, WL and WS, and may be classifiedinto three or more types which are different from each other in the sizeof the communication area and the transmitting interval.

[0177] A detailed procedure of this embodiment will now be describedreferring to its main flowcharts of FIGS. 24 and 25 and its welcomeprocess flowchart of FIG. 26. In these drawings, the contents of processin blocks denoted by same numerals are identical to those in FIGS. 4, 5,and 9 and will be explained in no more detail but their differentaspects.

[0178] Referring to FIG. 24, when the driver opens the door fordisembarkation, the procedure goes from Step S10 to Step S11W forexamining whether the WREC flag is 1 or not, i.e. the W code is receivedor not from the entry key 50. At the disembarkation, this step judges“NO” and the WSTM flag is turned to 1 at Step S12W to select thetransmission of the W small response demand signal WS. Step S13 followsfor enabling the intermittent transmission of the W small responsedemand signal WS with timer interruption.

[0179] The timer interruption for the intermittent transmission iscarried out at the interval of u seconds as clearly illustrated in FIGS.22 and 23. More specifically, the A and B response demand signals in theflowchart of FIG. 20 are replaced with the W large and W small responsedemand signals WL, WS, respectively. As the driver or the entry keysteps out from the vehicle and receives the W small response demandsignal, it sends back the W code in response. The W code is thenreceived by the vehicle mounted receiver allowing Step S14 to judge“YES” and the welcome process at Step S18 follows.

[0180]FIG. 26 illustrates the flowchart of the welcome process which isto be combined with FIG. 10. The operation is first explained when thedriver disembarks and its entry key departs from the vehicle. As the Wcode transmitted from the entry key responding to the reception of the Wsmall response demand signal WS from the vehicle is received by thevehicle, it is judged “YES” at Step S301 and the procedure goes to StepS302. If it is judged “NO”, the procedure jumps to Step S221 in FIG. 10.At Step S302, the WREC flag indicating the reception of the W code isshifted to 1.

[0181] This is followed by a sequence of Steps S303 to S306 for updatingby one the count of the W counter which represents the number ofreceptions of the W code (the count incremented to 1 by the firstreception), shifting the WLTM flag to 1 for selecting the transmissionof the W large response demand signal, turning the OUT flag to 0 forregistering that the entry key is within the communication area of the Wlarge response demand signal WL, and resetting the timer TOUT settingtime for detecting that the entry key is no more close to the vehicle,respectively.

[0182] Then, it is examined at Step S307 whether the count of the Wcounter is 1 or not. As the count is 1 and judged “YES” by now, theprocedure advances to Step S308 for setting and initiating the firsttimer for the receiving interval with the time v and then returns backto Step S2 in FIG. 24. At the next cycle of receiving the W code, StepsS307 judges “NO” and the procedure goes to Step S309 where it isexamined whether the remainder of the count of the W counter divided by2 is 0 or not, i.e. whether the count of the W counter is an odd numberor an even number.

[0183] As the count is 2 and it is judged “YES”, the second timer TWR2is equally set to v and initiated at Step S310. Then, Step S311 followsfor examining whether the first timer TWR1 is counted up or not. Asdescribed previously referring with FIG. 22, the W codes arecontinuously released in response to the W large and small responsedemand signals WL and WS for a while after the disembarkation and canthus be received before the timers are timed up. Accordingly, Step S311judge “NO”.

[0184] Therefore, the procedure advances to Step S312 for maintainingthe unlocked state of the door. When the reception of the next W codeincreases the count of the W counter to 3, the procedure goes from StepS309 to Step S314 for setting and initiating the first timer TWR1 withthe time v. It is then examined at Step S315 whether the second timerTWR2 is counted up or not.

[0185] While the entry key departs not far enough from the vehicle, StepS315 judges “NO” as described above and the unlocked state of the dooris maintained at Step S312. When the entry key departs far enough fromthe vehicle and is disabled to receive the W small response demandsignal WS, it is then judged “YES” at Step S315 and the procedure goesto Step S316 where the door of the vehicle is locked. Also, when StepS311 judges “YES” upon an even number of receiving times of the W code,the door is locked at Step S318.

[0186] As the entry key 50 departs further from the vehicle, it isdisabled to receive the W large response demand signal WL and fails todeliver the corresponding W code to the vehicle. It is then judged “NO”at Step S14 in FIG. 24 and the procedure goes from Steps S15A and S30 toStep S35. At the time, Step S35 judges “YES” and the initialization isexecuted at Steps S36W to S39W and S40. More particularly, the W counteris reset to zero, the first timer TWR1 and the second timer TWR2 arereset, the WSTM flag is turned to 0, and the OUT flag is shifted to 1.

[0187] The action of automatically unlocking the door will now beexplained when the driver carrying the entry key 50 moves towards thevehicle for embarkation. As the entry key 50 steps into thecommunication area of the W large response demand signal WL and receivesthe signal WL, it releases the corresponding W code. When the W code isreceived for the first time and judged at Step S301 in FIG. 26 that itis valid, the same process at Steps S302 to S307 are repeated.

[0188] More specifically, the W counter is reset to 1, the WLTM flag isshift to 1, the OUT flag is shifted to 0 for registering that the entrykey is within the communication area, and the timer T-OUT is reset. Atthe time, Step S307 judges “YES” and the first timer TWR1 is set to v atStep S308 before the welcome process is terminated.

[0189] As the reception of the next W code causes Step S307 to judge“NO” and Step S309 to judge “YES”, the second timer for the receivinginterval TWR2 is set with v at Step S310. Step S311 follows where it isjudged “YES” because the entry key 50 receives only the W large responsedemand signal WL and the interval of the W code is long enough, hencemaintaining the locked state of the door.

[0190] Also, when the procedure goes from Step S309 to Steps S314 and315, the locked state of the door is maintained at Step S316. As theentry key comes closer to the vehicle and receives too the W smallresponse demand signal WS, Step S311 or S315 judges “NO” permitting thedoor to be unlocked.

[0191] When the driver opens the door, steps into the vehicle, and shutsup the door, it is then judged “YES” at Step S6 (FIG. 24) and the timerinterrupted transmission of the I response demand signal is enabled atStep S8. As described with the first embodiment, when the I codecomparison is confirmed, the action of the engine is enabled. As theignition switch IGN SW is turned by the driver to the ON position, theengine starts running and simultaneously, the transmission of the Wresponse demand signals and the I response demand signal is stopped.Then, the flags are initialized at the steps in Block S41 (FIG. 25).

[0192] According to this embodiment, while the two types, WL and WS, ofthe response demand signal can successfully be switched from one toanother by changing only the output level of the response demand signalfrom the vehicle mounted transmitter, the response code released fromthe entry key is used only of one type, W code. Therefore, thetransmitter and receiver arrangements as well as the code identificationfunction will significantly be simplified, thus contributing to thelower cost and the ease of maintenance.

[0193] Although both the unlocking and locking actions of the door areautomatically controlled according to the reception of response signalto the response demand signals on the vehicle mounted receiver in theembodiments mentioned above, it will clearly be understood by thoseskilled in the art to automate only one of the two actions for moresimplicity.

[0194] According to the present invention recited in claims 1 and 2, thedistance from the vehicle to the user carrying the portabletransmitter/receiver (entry key) can precisely be identified thus tocontrol the vehicle mounted device such as the door(s) at an optimumlength of the distance, hence improving the utility of controlling thevehicle mounted device such as unlocking and locking the door(s) iscompatible with improvement in the anti-thief function.

[0195] According to the present invention recited in claim 3, thedistance from the vehicle to the user carrying the portabletransmitter/receiver can be identified on the basis of the intervalbetween receiving timings of the sent-back response signal on thevehicle even if the characteristic codes included in the responsesignals are not different each other, which response signals are sentback from the portable transmitter/receiver in response to a pluralitykinds of the response demand signal receivable within their respectivesizes of the predetermined ranges which are different each other. Hence,the vehicle mounted device can favorably be controlled depending on thedistance as well as the construction of the transmitter of the portabletransmitter/receiver and the code identifying action of the controllingmeans on the vehicle can significantly be simplified.

[0196] According to the present invention recited in claim 4, theresponse signal is also released at intervals of time from the portabletransmitter/receiver, thus providing the same effects and advantages asdescribed just above relating to the claim 3 invention.

[0197] According to the present invention recited in claim 5, as theresponse signals released from the portable transmitter/receiver inresponse to reception of the response demand signal are different eachother based on the different sizes of the receivable ranges of thedemand signals, the distance from the vehicle to the portabletransmitter/receiver can be identified only from the response signalreceived and the optimum control of the device mounted on the vehiclecan be performed in accordance with the distance.

[0198] According to the present invention recited in claims 6 and 7, atthe disembarkation of the user, as the portable transmitter/receivercarried by the user departs far from the vehicle, the transmission ofthe response demand signal receivable in a predetermined wider size ofthe range is executed, while the transmission of the response demandsignal receivable in a predetermined smaller size of the range iscanceled. As the potable transmitter/receiver comes from far towards thevehicle, on the other hand, the transmission of the response demandsignal with a smaller predetermined receivable range is not executedbefore the response signal responding to the response demand signal withthe largest predetermined receivable range is received by the vehicle.

[0199] More particularly, while the portable transmitter/receiver is outof the largest predetermined receivable range, the response demandsignal receivable in the largest predetermined range only istransmitted. Only when the response signal responding to the responsedemand signal receivable in the largest predetermined range is receivedby the vehicle, the transmission of the response demand signalreceivable in a smaller size of the predetermine range and used foractually controlling the unlocking and locking of the door is executed.Therefore, the transmission of the response demand signal is minimizedhence reducing the consumption of a power from a battery equipped on thevehicle.

[0200] According to the present invention recited in claim 8, the usercarrying the portable transmitter/receiver in the vehicle can preciselybe acknowledged, and the vehicle mounted device in the vehicle iscontrolled on the basis of the response signal from the portabletransmitter/receiver responding to a particular type of the responsedemand signal receivable within the vehicle, hence improving theanti-thief function.

[0201] In brief, the present invention allows the entry key to receivethe response demand signal for a wider communication area and send backa response signal to the vehicle, and the vehicle to transmit theresponse demand signal for a smaller communication area only when theresponse signal from the entry key is examined and qualified to be validby its welcome code comparison. In other words, even if any other personor object not relating to the vehicle is within the communication area Ashown in FIG. 13, no transmission of the B response demand signal ispermitted.

[0202] Accordingly, the transmission of the B response demand signal foractually controlling the locking and unlocking action of the door isminimized hence favorably reducing the consumption of a power in thebattery. Also, while the power consumption is minimized, thetransmission of the response demand signals can be executed at optimumintervals of time for a relatively smaller size of the communicationarea corresponding to the distance from the entry key to the vehiclethus to precisely control the vehicle mounted components, for example,automatically unlocking and locking the door of the vehicle. Moreparticularly, the control over the vehicle mounted components with theentry key can be made in compatibility with the energy saving. Inpractice, while the power consumption is minimized, the anti-thieffunction can be realized at higher utility.

[0203] Moreover, as different types of the response demand signals aretransmitted from the vehicle at intervals of time, the transmission ofthe response demand signal for a wider communication area is executed atintervals of a longer duration. This permits the control system toreadily acquire the distance from the vehicle to the entry key on thebasis of the interval between receiving timings of the response signalfrom the entry key without discriminating the response demand signalsand the response signals received, respectively, from each other andthus to favorably control the vehicle mounted components such as doors.Accordingly, the overall system can further be simplified inconstruction and operation.

1 (Canceled). 2: A remote control system for a vehicle comprising: atransmitter mounted on the vehicle for transmitting a response demandsignal receivable within a predetermined range outside the vehicle; aportable transmitter/receiver for sending back a response signal inresponse to reception of the response demand signal; a receiver mountedon the vehicle for receiving the response signal sent back from theportable transmitter/receiver; and a controlling means for controllingvehicle-mounted components responding whether the receiver receives theresponse signal or not, said transmitter arranged to transmit aplurality of response demand signals receivable within differentcorresponding predetermined ranges, said controlling means arranged toidentify that the portable transmitter/receiver exists within thelargest predetermined receivable range and to make the transmittertransmit another response demand signal receivable within apredetermined range which is smaller than the largest size of thepredetermined range in addition to the response demand signal receivablein the largest size of the predetermined range when a response signal isreceived by the receiver, which response signal corresponds to receptionof particular response demand signal being receivable within the largestpredetermined receivable range and, to control at least either unlockingor locking of a door(s) of the vehicle depending on whether a responsesignal is received or not by the receiver, which response signalcorresponds to reception of the other response demand signal than aparticular one being receivable within the largest predeterminedreceivable range. 3-5 (Canceled). 6: A remote control system for avehicle according to claim 2, further comprising a disembarkationdetecting means for detecting the disembarkation of a user, wherein whenthe disembarkation of the user is detected, a response demand signalreceivable within the smallest size of the predetermined range istransmitted from the transmitter, and when the response signal showingreception of the response demand signal receivable in the smallest sizeof the predetermined range is no more received by the receiver mountedon the vehicle, a second response demand signal receivable within thesecond smallest size of the predetermined range is begun to betransmitted from the transmitter in addition to the response demandsignal receivable in the smallest size of the predetermined range and,in a similar manner, a response demand signal receivable within arelatively larger size of the predetermined range is transmitted insequence from the transmitter. 7: A remote control system for a vehicleaccording to claim 2 wherein when the response signal to the responsedemand signal receivable within the largest size of the predeterminedrange is received after it is not received by the receiver mounted onthe vehicle, the response demand signal receivable within second largestsize of the predetermined range is transmitted from the transmitter inaddition to the response demand signal receivable within the largestpredetermined range and then a response demand signal receivable withina relatively smaller size of the predetermined range is transmitted insequence from the transmitter. 8: A remote control system for a vehicleaccording to claim 2 wherein further comprising an embarkation detectingmeans for detecting the embarkation of a user, wherein when theembarkation of the user is detected by the embarkation detecting means,a response demand signal receivable within the vehicle is transmittedfrom the transmitter, and when the response signal to the responsedemand signal receivable inside the vehicle is received by the receiver,action of an engine is enabled. 9-12 (Canceled).